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• How to trim and merge using Fluent FFMpeg ?

  29 juillet 2016, par John D.

  Here’s what I want to do with fluent-ffmpeg :

  I have 3 input files. An intro, main, and outro video. I wish to merge the three, while trimming the main video. Here is my code :

  var ffmpegCommand = ffmpeg();
  
  ffmpegCommand.addInput(introVideo);
  
  ffmpegCommand.addInput(mainVideo).seekInput(20).duration(3);
  
  ffmpegCommand.addInput(outroVideo);
  
  ffmpegCommand.on('error', function(err, stdout, stderr){
  
    console.log("FAILED!\n\t"+err+"\n\t"+stdout+"\n\t"+stderr);
  
  });
  
  ffmpegCommand.on('end', function(){
  
    console.log('COMPLETE!');
  
  });
  
  ffmpegCommand.on('start', function(commandLine) {
  
    console.log('Spawned Ffmpeg with command: ' + commandLine);
  
  });
  
  ffmpegCommand.mergeToFile('final.mp4', './vid_files/tmp');

  The program executes fine, but when I ffplay final.mp4, the result is that introVideo plays then the video appears to freeze. According to the fluent-ffmpeg documentation, it states "Each of these [Input options] methods apply on the last input added". So I can’t figure out why that syntax doesn’t seem to work...

  How can I trim the main video to send to mergeToFile ?

  Note that this works fine if I don’t have .seekinput(20).duration(3) on the second addInput.

  Oh, here’s the outputted commandLine value :

  ffmpeg -i ./vid_files/intro.mp4 -ss 20 -i ./vid_files/main.mp4 -i ./vid_files/outro.mp4 -y -filter_complex concat=n=3:v=1:a=1 -t 3 final.mp4

• Change pitch of audio file without altering the duration of audio file (FFMPEG)

  13 janvier 2016, par VickyS

  I am in a bit of trouble.
  I am working on FFMPEG for android and now my task is to modify the pitch of the audio file without altering the duration of the audio file.

  I used these commands but they alter the duration :

  ffmpeg -i /sdcard/emoj/final.wav -filter:a atempo=1.5 -vn /sdcard/emoj/final1.wav
  
  
  
  ffmpeg -i /sdcard/emoj/final.wav -filter:a asetrate=r=35K -vn /sdcard/emoj/final1.wav

  I know I can use Sonic NDK for this purpose. But I want to know if its possible with the help of FFMPEG.
  In documentation I have seend something called "Rubberband" I think that can help. But I dont know how to use that.

  I just want the command to do that.
  I would appreciate any help in this regard.

• How to get video frame for a specific time from mp4

  11 décembre 2015, par man-r

  i have an mp4 video byte array and i need to generate a thumbnail for it using its middle frame (e.g. if the video length is 10 seconds then i need to get the picture from 5th second).

  i managed to parse through the file and extract its boxes (atom). i have also managed to get the video length from the mvhd box. also i managed to extract
  1. the time-To-Sample table from stts box,
  2. the sample-To-Chunk table from stcs box,
  3. the chunk-Offset table from stco box,
  4. the sample Size table from stsz box,
  5. the Sync Sample table from stss box

  i know that all the actual media are available in the mdat box and that i need to correlate the above table to find the exact frame offset in the file but my question is how ? the tables data seems to be compressed (specially the time-To-Sample table) but i don’t know how decompress them.

  any help is appreciated.

  below are code samples

  code to convert byte to hex

  public static char[] bytesToHex(byte[] bytes) {
  
      char[] hexChars = new char[bytes.length * 2];
  
      for ( int j = 0; j < bytes.length; j++ ) {
  
          int v = bytes[j] & 0xFF;
  
  
  
          hexChars[j * 2] = hexArray[v >>> 4];
  
          hexChars[j * 2 + 1] = hexArray[v & 0x0F];            
  
      }
  
      return hexChars;
  
  }

  code for getting the box offset

  final static String MOOV                          = "6D6F6F76";
  
  final static String MOOV_MVHD                     = "6D766864";
  
  final static String MOOV_TRAK                     = "7472616B";
  
  final static String MOOV_TRAK_MDIA                = "6D646961";
  
  final static String MOOV_TRAK_MDIA_MINF           = "6D696E66";
  
  final static String MOOV_TRAK_MDIA_MINF_STBL      = "7374626C";
  
  final static String MOOV_TRAK_MDIA_MINF_STBL_STSD = "73747364";
  
  final static String MOOV_TRAK_MDIA_MINF_STBL_STTS = "73747473";
  
  final static String MOOV_TRAK_MDIA_MINF_STBL_STSS = "73747373";
  
  final static String MOOV_TRAK_MDIA_MINF_STBL_STSC = "73747363";
  
  final static String MOOV_TRAK_MDIA_MINF_STBL_STCO = "7374636F";
  
  final static String MOOV_TRAK_MDIA_MINF_STBL_STSZ = "7374737A";
  
  
  
  static int getBox(char[] s, int offset, String type) {
  
      int typeOffset = -1;
  
      for (int i = offset*2; i-1) {
  
                  break;
  
              } 
  
          }
  
          i+=(size*2);
  
      }
  
  
  
      return typeOffset;
  
  }

  code for getting the duration and timescale

  static int[] getDuration(char[] s) {
  
      int mvhdOffset = getBox(s, 0, MOOV_MVHD);
  
      int timeScaleStart = (mvhdOffset*2) + (4 + 4 + 1 + 3 + 4 + 4)*2;
  
      int timeScaleEnd   = (mvhdOffset*2) + (4 + 4 + 1 + 3 + 4 + 4 + 4)*2;
  
  
  
      int durationStart  = (mvhdOffset*2) + (4 + 4 + 1 + 3 + 4 + 4 + 4)*2;
  
      int durationEnd    = (mvhdOffset*2) + (4 + 4 + 1 + 3 + 4 + 4 + 4 + 4)*2;
  
  
  
      String timeScaleHex = new String(Arrays.copyOfRange(s, timeScaleStart, timeScaleEnd));
  
      String durationHex = new String(Arrays.copyOfRange(s, durationStart, durationEnd));
  
  
  
      int timeScale = Integer.parseInt(timeScaleHex, 16);
  
      int duration = Integer.parseInt(durationHex, 16);
  
  
  
      int[] result = {duration, timeScale};
  
      return result;
  
  }

  code to get the time-To-Sample table

  static int[][] getTimeToSampleTable(char[] s, int trakOffset) {
  
      int offset = getBox(s, trakOffset, MOOV_TRAK_MDIA_MINF_STBL_STTS);
  
      int sizeStart = offset*2;
  
      int sizeEnd   = offset*2 + (4)*2;
  
  
  
      int typeStart = offset*2 + (4)*2;
  
      int typeEnd   = offset*2 + (4 + 4)*2;
  
  
  
      int noOfEntriesStart = offset*2 + (4 + 4 + 1 + 3)*2;
  
      int noOfEntriesEnd   = offset*2 + (4 + 4 + 1 + 3 + 4)*2;
  
  
  
      String sizeHex = new String(Arrays.copyOfRange(s, sizeStart, sizeEnd));
  
      String typeHex = new String(Arrays.copyOfRange(s, typeStart, typeEnd));
  
      String noOfEntriesHex = new String(Arrays.copyOfRange(s, noOfEntriesStart, noOfEntriesEnd));
  
  
  
      int size = Integer.parseInt(sizeHex, 16);
  
      int noOfEntries = Integer.parseInt(noOfEntriesHex, 16);
  
  
  
      int[][] timeToSampleTable = new int[noOfEntries][2];
  
  
  
      for (int i = 0; icode>